1. Field of the Invention
The present invention relates to wrist-portable equipment, and more particularly to a wrist-portable apparatus provided with a display member rotating independently and separately from a gear train of circumferential divisional hour/minute/second.
2. Description of the Prior Art
In a wrist-portable equipment, a technology for rotating and operating a display member provided in an interior of a case member by a stem provided in the outside of the case member is currently known. FIG. 8 is a plan view showing a body of a conventional wristwatch 100. FIG. 9 is a side elevational cross-sectional view showing a primary part of the wristwatch 100 described in FIG. 9. In FIGS. 8 and 9, the wristwatch 100 has a letter plate 102 and a scale ring 103 within a watch case 101.
Also, a stem 104 for rotating the scale ring 103 is mounted independently and separately from a stem 105 for correcting hour/minute/second hands, on the side surface portion of the watch case 101. This stem 104 is made of a metal member and has a cup-like shape. A cup bottom portion of this stem 104 is formed integrally so as to cover one end portion of a cylindrical operating shaft 106 made of a metal member. The operating shaft is inserted into the watch case 101 by passing through a pipe 107 which is securely provided to and penetrates through the watch case.
A gear 109 made of plastic or metal material is fitted into the vicinity of a tip end portion 108 of the inserted operating shaft 106. This gear 109 is fixed to the operating shaft 106 by means of a ring-shaped fastening member 110 made of metal material. On the other hand, the above-described scale ring 103 is disposed with its display portion 111 facing the side of a watch glass 112, its bottom portion 113 facing the side of the letter plate 102 and its side portion 114 facing the inner wall of the watch case 101. The scale ring 103 has a rack 116 on a circumferential portion of its back surface. The scale ring 103 is engaged with the above-described gear 109 in this rack 116.
In this wristwatch 100, when the scale ring 103 is to be adjusted, the stem 104 is pinched by the fingers to rotate it in the axial direction by the fingers. Then, the operating shaft 106 formed integrally with the stem 104 is also rotated and the gear 109 fixed at its tip end portion 108 is also rotated. When the gear 109 is rotated, the rack 116 of the scale ring 103 engaging therewith is fed so that the scale ring 103 is also rotated. Thus, it is possible to adjust the scale ring 103 in a desired position by controlling the stem 104 while watching the scale ring through the glass 112 of the watch.
Thus, in the conventional wristwatch 100, the scale ring 103 and the stem 104 mounted on the side surface portion of the watch case 101 are always coupled with each other through the operating shaft 106 and the gear 109. For this reason, there are cases where, when it is mounted on the wrist, the stem 104 is rotated due to its contact with the body, wear cloth or the like and the scale ring 103 is displaced as a result. For this reason, in the conventional wristwatch 100, a ring-shaped frictional member 117 made of elastic system material is provided on the inner wall surface of the stem 104 to thereby generate friction with the pipe 107 to suppress such an unnecessary rotation and to prevent malfunction of the scale ring 103. Note that, the member 118 provided on the bottom surface portion 113 of the scale ring 103 is an annular cushion 118 made of elastic system material for preventing the displacement of the scale ring 103 during the rotation. The member 119 provided in the intermediate portion of the operating shaft 106 is an annular water-proof packing 119 made of elastic system material for sealing a gap between the operating shaft 106 and the pipe 107.
However, the malfunction of the above-described scale ring 103 could not be completely prevented by the provision of the cushion 117 as described above. Also, it is necessary to consider frequent and vigorous contact which may take place between the stem 104 and the body or the like in the case where the wrist-portable equipment is worn while playing a sport or the like. On the other hand, unduly increasing the fastening degree of the above-described cushion 117 in order to prevent the above-described malfunction leads to the necessity of excessive force for rotating the stem 104 for performing adjustment of the scale ring 103. Thus, there is a certain limitation regarding this approach.